Department of Chemistry , University of California , Irvine , California 92697-2025 , United States.
Inorg Chem. 2018 Aug 20;57(16):9728-9737. doi: 10.1021/acs.inorgchem.8b00618. Epub 2018 Jul 3.
Double deprotonation of bis(2-mercapto-4-methylphenyl)amine ([SNS]H) followed by addition to NiCl(PR) in air-free conditions afforded [SN(H)S]Ni(PR) (1a, R = Cy; 1b, R = Ph) complexes, characterized as diamagnetic, square-planar nickel(II) complexes. When the same reaction was conducted with 3 equiv of KH, the diamagnetic anions K{[SNS]Ni(PR)} were obtained (K[2a], R = Cy; K[2b], R = Ph). In the presence of air, the reaction proceeds with a concomitant one-electron oxidation. When R = Cy, a square-planar, S = / complex, [SNS]Ni(PCy) (3a), was isolated. When R = Ph, the bimetallic complex {[SNS]Ni(PPh)} ({3b}) was obtained. This bimetallic species is diamagnetic; however, in solution it dissociates to give S = / monomers analogous to 3a. Complexes 1-3 represent a hydrogen-atom-transfer series. The bond dissociation free energies (BDFEs) for 1a and 1b were calculated to be 63.9 ± 0.1 and 62.4 ± 0.2 kcal mol, respectively, using the corresponding p K and E°' values. Consistent with these BDFE values, TEMPO reacted with 1a and 1b, resulting in the abstraction of a hydrogen atom to afford 3a and 3b, respectively.
双去质子化的双（2-巯基-4-甲基苯基）胺([SNS]H)，在无空气条件下与 NiCl(PR)加成，得到顺磁性、平面正方形镍(II)配合物[SNS]Ni(PR)（1a，R=Cy；1b，R=Ph）。当相同的反应与 3 当量的 KH 进行时，得到了抗磁性阴离子 K{[SNS]Ni(PR)}（K[2a]，R=Cy；K[2b]，R=Ph）。在空气存在下，反应会伴随单电子氧化进行。当 R=Cy 时，得到平面正方形、S=1/2 的配合物[SNS]Ni(PCy)（3a）。当 R=Ph 时，得到双金属配合物{[SNS]Ni(PPh)}({3b})。该双金属物种为抗磁性；然而，在溶液中它会解离，得到类似于 3a 的 S=1/2 单体。配合物 1-3 代表一个氢原子转移系列。通过相应的 p K 和 E°'值，计算出 1a 和 1b 的键离解自由能（BDFE）分别为 63.9±0.1 和 62.4±0.2 kcal mol。与这些 BDFE 值一致，TEMPO 与 1a 和 1b 反应，分别从 1a 和 1b 中抽取一个氢原子，得到 3a 和 3b。
